1. Field
Embodiments relate to an organic light emitting display, and more particularly, to a power supplying apparatus for an organic light emitting display.
2. Description of the Related Art
Among flat panel displays (FPDs), organic light emitting displays are adapted to display an image using organic light emitting diodes (OLED) that generate light by re-combination of electrons and holes. Organic light emitting displays may be advantageous over other flat panel displays by having relatively high response speed and/or by being capable of being driven with relatively low power consumption.
In general, organic light emitting displays include a pixel unit having a plurality of pixels, a scan driver for supplying scan signals to the pixel unit, a data driver for supplying data signals to the pixel unit, and a power supplying unit for supplying pixel power sources ELVDD and ELVSS to the pixel unit.
More particularly, the power supplying unit provides a predetermined reference voltage to the scan driver and the data driver other than the pixel power source. The power supplying unit provides the high level voltage VGH and the low level voltage VGL of scan signals to the scan driver and provides a gamma reference voltage VCC for generating data signals to the data driver.
The pixels emit light components with brightness components corresponding to the data signals supplied in synchronization with the scan signals when the scan signals are supplied so that the pixel unit displays a predetermined image. In organic light emitting displays, emission brightness components of the pixels are affected by the voltages of the pixel power sources. That is, the pixel power sources determine the emission brightness components of the pixels with the data signals.
Therefore, the scan signals are first applied and then, the data signals are applied in synchronization with the scan signals in order to have the organic light emitting display normally driven.
However, in a conventional power supplying unit, a DC-DC converter is used in order to additionally generate the power sources. Due to the forward direction characteristic of a diode and an inductor included in the DC-DC converter, power sequence in an unintended order may be generated due to a current path formed within a short time before the DC-DC converter is normally driven.